1. Field of the Invention
The present invention relates to a heating device for a vehicle wherein an auxiliary heating source is provided for heating recirculating water for heating a cabin of the vehicle.
2. Description of Related Art
The Japanese Unexamined Patent Publication (Kokai) No. 2-246823 discloses a viscous heater which is used as an auxiliary heating source for a heating device for a cabin of a vehicle. The viscous heater includes a front and rear housings which are in axial face-to-face contact and are connected by means of circumferentially spaced bolts which pass through the front and rear housings. Inside the housings, a heat generating chamber and a water jacket are formed so that the water jacket is located outside the heat generating chamber. Formed in the housing are an inlet port for introducing the recirculating water into the water jacket and an outlet port for removing the recirculated water into an outside heating circuit. A rotating shaft is rotatably supported by the front housing via a bearing and a rotor is fixedly connected to the rotating shaft so that the rotor is rotated in the heat generating chamber when the rotating shaft is rotated by a crankshaft of an internal combustion engine. The heat generating chamber is formed with an inner surface, which, at a small distance, faces an outer surface of the rotor. These faced surfaces are formed with labyrinth grooves, which are adjacent to each other. A viscous fluid is filled in the gap between the inner surface of the heat generating chamber and an outer surface of the rotor.
In the operation of the viscous heater in the above patent, an application of a rotating movement to the drive shaft causes the rotor to be rotated in the heat generating chamber, so that the viscous fluid in the gap between the inner surface of the heat generating chamber and the outer surface of the rotor is subjected to shearing, thereby generating a heat. Then, a heat exchange of the heat of the viscous fluid with respect to the recirculating water occurs, thereby causing the recirculating water to be heated, which is fed to the heating system for heating the cabin of the vehicle.
In the viscous heater of the prior art, the inlet and outlet ports for the recirculating water are connected to the outside conduits for an engine cooling water by using unions formed as tubular portions extending integrally and in parallel from the housing. However, the arrangement of the outside conduits as combined with a cooling water recirculating system is different between types of vehicles in which the heater is mounted. Furthermore, an arrangement of unions for connecting the heater with the outside heating conduit is also different between the types of the vehicle to which the viscous heater is mounted. As a result, in the structure of the viscous heater, where the unions are integrated with the housing, different types of housings are required in accordance with the types of the vehicle, resulting in an increase in production cost.